JPS61140199A - Manufacture of multilayer printed circuit board and multilayer printed circuit board manufacture thereby - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a multilayer printed circuit board, in which the associated conductors of a first circuit layer are connected to the associated conductors of one or more other circuit layers. or at least one recess in the first circuit layer at the location of the conductor to be interconnected so as to contact a plurality of conductors.
The conductors of different circuit layers are interconnected by forming a conductor.

The invention also relates to multilayer printed circuit boards produced by the method in which conductors of different layers are interconnected.

Methods of interconnecting printed circuit layers on opposite sides of electrically insulating flakes or two mutually insulated circuit layers of a printed circuit board are described, for example, in US Pat. No. 3,346,450. This U.S. patent application discloses a push-down technique in which contact is formed between the first and second layers without the second layer being penetrated.
) are listed. Temporary connections formed in this way can be made by plating the recesses with copper or gold, for example.
It must be electrically and mechanically reinforced with additional conductive material. In order not to penetrate into the second layer, the method according to the above-mentioned US patent application must be carried out on a rigid backing surface that does not deform during pressing. If the method is applied to electrically insulating foils with printed circuit layers, a temporary hard support surface is required, and if two
If applied to individual circuit layers, the substrate must be sufficiently rigid.

It is an object of the present invention to provide a method for manufacturing a multilayer printed circuit board having conductors interconnected in different layers, which can be made of fiberglass or other materials commonly used in printed circuit boards. This allows the use of less rigid layers, such as reinforced epoxy resin support surfaces. Another object of the invention is to provide a method that can also be used in multilayer printed circuit boards containing two or more circuit layers. Another object of the invention is to provide a method in which the contact between the circuit layers is good at the location of the recesses, so that no further reinforcement of the contact by additional conductive material is required.

These objectives are achieved according to the invention by the method described in the opening article, in which a multilayer printed circuit board is placed on a deformable substrate at least during the pressing process, and the first circuit layer is Deformation of circuit layers and insulating layer(s) between circuit layers such that the circuit layers are pushed down beyond the level of other circuit layer(s) and thus the circuit layers are interconnected at recessed locations. It is characterized by causing the deformation of

A method of interconnecting conductors on opposite sides of a flexible foil is known from West German patent application DE 2,107,591, in which the first layer is pressed down beyond the level of the second layer, but The layers do not come into mechanical contact, and an electrically conductive connection is not achieved until the lugs formed by pressing down are bent further and soldered. The method according to the above-mentioned West German patent application is permanent.
) Can only be used on flexible flakes without a support surface. Additionally, this method uses dice.

In a multi-layer printed circuit board according to a highly efficient embodiment of the present invention, one side of the deformable board comprises a permanent circuit layer and a permanent circuit. Thus, the substrate, circuit layer, and insulating layer together make up a printed circuit board.

If desired, the connections can be made, e.g. by flow soldering operation (flOW).
-3ol(lerin(l0peration)) can be further reinforced after the penetration, where preferably a solder-screen lacquer (solder-screen lacquer)
ing 1acquer) is applied to the substrate outside the area where the connection is to be made. In this flow soldering operation, solder is applied to the cavity formed by the penetration.

Soldering joints formed in this way are suitable for mounting electrical components without stressing the terminals, which means that after temporary fixing, for example with adhesive, the same or another soldering joint cannot be operated. Can be installed.

This method according to the invention may also be applied to flexible electrically insulating foils with conductor layers on both sides. Once the depression has been formed, the flakes are placed on a temporary support plate that can be deformed to a sufficient extent.

Thermoplastic materials are most suitable for this purpose and, if necessary, the deformation conditions can be satisfied by increasing the temperature.

If the method of the invention is used to interconnect conductors on opposite sides of the flexible foil, the cavities will have parallel sides. This is because the deformation of the material of the temporary support substrate creates a counterpressure during depression such that the material originally located on this support substrate is deformed to such an extent that it is clamped into the cavity. Because it does.

Embodiments of the method according to the invention will be explained in detail by means of the drawings.

FIG. 1 is a cross-sectional view of the part of the substrate supporting conductor layers 2 and 4 separated from each other by an insulating layer 3. FIG. The substrate 1 is formed from materials commonly used in the art, such as glass fiber reinforced epoxy resin with a layer thickness of 1.5111 and a glass transition temperature of 125°. The glass fibers should preferably not be arranged in a reticulated pattern, allowing indentations, particularly in the insulation layer 3, to be made independently. The conductor layers 2 and 4 consist of patterned copper layers, for example 35 μm thick. The insulating layer 3 may for example be made of the same material as the substrate 1 with a thickness of 75μ. The layers can be bonded together by known compression methods.

For example, by means of a conical push-down tool of hardened steel, the recess 5 is formed in such a way that the conductor layer 4 is compressed over the conductor layer 2.

This results in an annular contact 6 between the conductor layers 2 and 4. The bulge 7 is created, inter alia, around the depression 5 by the accumulation of the deformed insulating material 3. The bulges 7 are of small dimensions so as not to interfere with further mechanical processing of the multilayer printed circuit board, in contrast to, for example, bent or soldered lugs. For a conductor with a width of 0.511, a recess with a diameter of 0.2i+m is used, for example.

In FIG. 2, which is a cross-sectional view of a portion of a multilayer printed circuit board similar to that shown in FIG. 1, corresponding elements have circumferential reference numbers.

In this case, frustoconical
A push-down tool is used for machining. In the embodiment shown in FIGS. 1 and 2, the connection can be further reinforced by applying a conductive material, such as solder, in the recess. In the case of FIG. 1, the connection between layers 2 and 4 would be improved in the area of contact 6, and in the case of FIG. It will be.

Depending on the tool used for penetration or depression, the area of contact thus formed will look different in detail. Asymmetric push-down tools are also suitable. For example, the third
The figure shows a triangular depression tool, with which uneven square depressions can be formed. FIG. 4 shows a conical depression tool cut at an angle so that an oval recess can be formed. A suitable shape for such a truncated cone is, for example, an apex angle of the cone of about 50°, an end face making an angle of 10° with the axis of the cone and an elliptical end face with a length of 0.2 mm. is defined by the principal axis of In order to obtain the desired result, the above-mentioned dimensions must be adapted to the chosen material and layer thickness.

SUMMARY The present invention provides a method in which the insulating layer(s) are modified such that contact is made between the outermost layer and the appropriate conductor(s) of the next layer or layers. , relates to a method for interconnecting conductors of different layers of a multilayer printed circuit board by forming recesses in the associated conductors of the outermost layer.

The method can be suitably used in multilayer printed circuits on substrates and flexible multilayer printed circuits in electrically insulating foils.

In the latter case a temporary support surface is required for the pressing down process. The substrate or temporary support surface must be deformable to a sufficient degree.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a recess deformed by a conical push-down tool. FIG. 2 is a cross-sectional view of a recess deformed by a frustoconical tool. 3 and 4 are alternative embodiments of the push-down tool used in the method of the present invention. DESCRIPTION OF SYMBOLS 1... Board 2, 4... Conductor layer 3... Insulating layer 5... Recess 6... Contact 7... Rise 10... Triangular push-down tool 20... Diagonally cut conical push-down tool Patent applicant: NV Philips Fluoran Penf 7 Bricken

Claims (1)

Claims: 1. Conductors to be interconnected such that the associated conductor of the first circuit layer contacts the associated conductor or multiple associated conductors of one or more other circuit layers. A method of manufacturing a multilayer printed circuit board in which conductors of different layers are interconnected by forming at least one recess in a first circuit layer at a location, wherein the multilayer printed circuit board is placed on the deformable substrate and deforms the circuit layers and between the circuit layers such that the first circuit layer is pushed down beyond the level of the other circuit layers, thus interconnecting the circuit layers at recessed locations. A method for manufacturing a multilayer printed circuit board, characterized in that deformation of an insulating layer is caused. 2. In a multilayer printed circuit board in which the conductors of different layers are interconnected, manufactured by the method as claimed in claim 1, one side of the deformable board is connected to the invariant circuit layer and the insulating layer. A multilayer printed circuit board comprising a stack.